DS1 may have the opportunity to visit Japan with the Scouts in two years, when he'll be 15.
DH & I both agree that DS1 should go if he wants to. He will have two years to try and earn / raise most of the cost, and we could pay for the rest with that long to save for it.
There is also the possibility that DH could go. He is a Scout leader and could go as the medic, which means his place would be subsidised as he'd be working.
The question is: if you were a 15 year old boy travelling to the other side of the world with your friends on the trip of a lifetime, would it bother you to have your dad tagging along as part of the supervising team?